In applicants' pending application U.S. Ser. No. 08/113,709 filed Aug. 31, 1993, the effectiveness of 4-allylanisole as a repellent for Scolytidae in general is examined at length. Insect attack on healthy, damaged or weakened host trees, such as loblolly pines and other host trees (including e.g. all yellow pines including eastern and western species, eastern and western white pines, Norway spruce, Larch, eastern red cedar, eastern Hemlock, Fraser fir, Douglas fir, and other fir trees, and thus generally conifers) continues to be a significant commercial and ecological problem. Although certain insecticides have been established for limited protection of trees, the use of non-natural chemical insecticides itself has serious impacts on the environment, and ought be avoided, where possible. In particular, the use of a limited number of chemicals increases the risk of development of resistance in the pest population, alters the ecosystem by reducing species diversity, modifying the food chain and altering patterns of energy flow and nutrient cycling, and may adversely affect natural enemies of the pests, (the southern pine beetle, and members of the beetle family, Scolytidae in general). Coupled with the ecological dangers of using an insecticide is the fact that the high cost of labor and the high cost of the chemical products, along with the need to spray all surfaces for effective control, will generally restrict the use of topically applied chemicals. Thus, applicants' identification in the parent application of 4-allylanisole as a repellent to scolytids, a naturally produced component of the resin exuded by the potential host, provides an alternate method of protecting these hosts, which does not require spraying of all potential surfaces. In particular, application of the product as a concentrated liquid, carried on elution devices or applied directly to a portion of the tree, or as a vapor, may be used with good effectiveness.
The prior art in this field is, as a result of the desirability of selecting naturally-produced products, focused on components of resins produced by the host trees. Of all the references discussed in the parent application, Werner, Journal of Insect Physiology, 18:423-438, 1972 is perhaps the most complete. This reference identifies 4-allylanisole as an attractant for Ips grandicollis in purified form at 1% concentration. The article teaches one of skill in the art that an effective repellent for Scolytidae employing 4-allylanisole cannot be prepared. However, additional research by the author of the reference, Werner, Environmental Entomology, (in press) has in fact documented the discovery disclosed in the pending parent application, that 4-allylanisole is a repellent for scolytids.
Accordingly, it remains an object of those of skill in the art to develop alternatives to conventional insecticides, employing compounds selected from, or similar to, those naturally produced by the targeted host, as effective insect repellents.